SNMOD moves selected sounding data from an input sounding file to an output sounding file. INPUT PARAMETERS SNFILE *Sounding data file SNOUTF *Output sounding file SNPARM *Sounding parameter list AREA *Data area DATTIM *Date/time LEVELS *Vertical levels VCOORD *Vertical coordinate type TIMSTN *Times/additional stations MRGDAT *Merge data file flag/part type IDNTYP *STNM or STID PROGRAM DESCRIPTION SNMOD takes data from a GEMPAK sounding file, SNFILE, and writes it to an output GEMPAK sounding file, SNOUTF. This program can be used to subset the original dataset by time and/or stations and to change the levels and vertical coordinate. The output dataset may be either a merged or unmerged data set. If the output file does not exist, a new file will be created by this program. If a new file is created, MRGDAT will determine whether the output file will be a merged or unmerged dataset. Note that an error will result if the input dataset is merged and the output dataset is unmerged. The value of SNPARM will be ignored if the output dataset is unmerged. If a merged data file is to be created, SNPARM will specify the parameters to be included. In this case, if SNPARM = DSET, the parameters in the input dataset will be used. If the output file is an existing merged dataset, the parameters specified in SNPARM must be in the dataset. In this case, if SNPARM = DSET, the parameters in the output file will be used. If the output file is to be created, the maximum number of times and stations which can be stored in the file must be specified in TIMSTN. IDNTYP has been added to specify whether station numbers or station identifiers will be used in referring to stations. Generally, IDNTYP should be set to STNM to use station numbers. However, in datasets which do not have station numbers, or which have a single invalid number, character station identifiers must be used and IDNTYP must be set to STID. EXAMPLES 1. Put the mandatory data for stations in an area centered on IL at time 910819/1200 into a new unmerged sounding file, NEW.SND, which may contain 2 times and 150 stations. SNFILE = gemdata:hrcbob.snd SNOUTF = new.snd SNPARM = dset AREA = il DATTIM = 19/12 LEVELS = man VCOORD = pres TIMSTN = 2/150 MRGDAT = no IDNTYP = stnm 2. Add the stations at time 910819/00 to the file created in example 1. DATTIM = 19/00 3. Create an isentropic dataset containing the specified parameters with levels every 5 degrees. Include all the US stations. SNFILE = gemdata:hrcbob.snd SNOUTF = thta.snd SNPARM = thta;pres;mixr;uwnd;vwnd;psym AREA = @us DATTIM = all LEVELS = 250-450-5 VCOORD = thta TIMSTN = 4/150 MRGDAT = yes ERROR MESSAGES [SNMOD -1] Fatal error initializing TAE. [SNMOD -2] Fatal error reading TAE parameters. [SNMOD -3] Output file cannot be unmerged type. [SNMOD -4] A new file cannot be created with no times. [SNMOD -5] A new file cannot be created with no stations. [SNMOD -6] Parameter ... cannot be computed. [SNMOD -7] ... is character type; cannot be added to file. [SNMOD -8] Output vertical coordinate ... cannot be used. [SNMOD -9] No valid parameters were specified. [SNMOD -10] Time ... cannot be added to the output file. [SNMOD -11] Station ... cannot be added to output file. [SNMOD -12] Parms do not match those in output data set. [SNMOD -13] Output file name is blank.